Various types of electrical outlet receptacles have been provided for use in marine, commercial and industrial applications with an included interlocking mechanism to reduce the hazards of inserting into or withdrawing a plug from such a receptacle while the receptacle is in a live condition. A common application of this type of outlet receptacle involves refrigerated containers that are transported on land by trucks and on sea by ships. When these containers are transported on land, electrical power to drive the refrigeration system is provided by the transporter, such as the tractor pulling the container. When these containers are delivered for loading onto ships, however, the electrical plugs for powering the refrigeration unit must be plugged into a shore-side power source, and when on board a ship, they must be plugged into a source of electrical power on the ship. When the refrigerated container is at dockside or on board the ship, the source of electrical power should be sealed water-tight to protect against the wet environment and potential problems of corrosion and rust from salt water and salt air. Additionally, because the current is typically 220 volts or 440 volts with substantial amperage, it is important that the receptacle be provided with apparatus that prevents inserting or withdrawing a plug while the circuit is live, and which apparatus also switches off power to the receptacle when a plug is not present. While various means, most commonly involving o-ring seals, have been widely used to effect waterproof sealing of such units, problems have remained with respect to the interlocking mechanisms.
For example, in one such type of interlocking mechanism, a spring loaded operating member or pushrod is used to reset or turn on the circuit breaker. To operate the mechanism, a user pushes the spring loaded operating member inwardly of the interlock housing which in conjunction with an actuating member engages and moves a circuit breaker switch handle to a circuit completing position. The spring used to spring load the operating/actuating members is compressed upon inward movement of the operating member, thus provides resistance in the outward direction against the circuit breaker switch handle. Ideally, the size of the spring is selected to bc sufficiently weak not to trip the circuit breaker switch handle after it has been set. While it is known to use some type of pre-assembled clip internally of the interlock mechanism (luring transportation, which must be removed before use of the interlock mechanism, it has been discovered that interlock mechanisms employing such spring loaded operating members experience premature tripping of the circuit breaker during use in heavy vibration environments. When vibration is introduced with an amplitude in the axial direction of the actuating member, the actuating member may work its way out with assistance from the compressed spring thereby tripping the breaker. Therefore, a need exists for a device that will not allow premature tripping of a circuit breaker in heavy vibration environments.